/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineGroupsInterface.h
A structure for caching a list of people in the group and their roles
typedef [IGroupUserCollection](API\Plugins\OnlineSubsystem\Interfaces\IGroupUserCollection)< [FGroupMember](API\Plugins\OnlineSubsystem\Interfaces\FGroupMember) > IGroupRoster